Method and apparatus for performing signaling for reserved sub-band in wireless communication system

ABSTRACT

A wireless communication system and, more particularly, to a method for performing efficient signaling for a reserved sub-band in a wireless LAN system, and a method and an apparatus for signal transmission using the same. To this end, an STA provides resource allocation information for transmitting data to a plurality of STAs using an orthogonal frequency divisional multiple access (OFDMA) or multiple user MIMO (MU-MIMO) method; transmits the resource allocation information to the plurality of STAs; and transmits data to the plurality of STAs according to the resource allocation information. The entire frequency band may include a sub-band which is not used for the data transmission, and it is preferable that the resource allocation information includes a resource allocation bitmap having a form common to the plurality of STAs and indication information which informs a sub-band, from among the entire frequency band, which is not used for the data transmission.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/549,980, filed on Aug. 23, 2019, which is a continuation of U.S.patent application Ser. No. 15/505,906, filed on Feb. 22, 2017, now U.S.Pat. No. 10,432,364, which is the National Stage filing under 35 U.S.C.371 of International Application No. PCT/KR2015/008743, filed on Aug.21, 2015, which claims the benefit of U.S. Provisional Application No.62/040,430, filed on Aug. 22, 2014, the contents of which are all herebyincorporated by reference herein in their entirety.

TECHNICAL FIELD

The following description relates to a wireless communication systemand, more particularly, to a method of efficiently signaling unusedsubbands in a wireless local area network (WLAN) and a signaltransmission apparatus and method using the same.

BACKGROUND ART

Although the below-described signal transmission methods are applicablevarious wireless communication systems, a wireless local area network(WLAN) system will be described as an example of a system, to which thepresent invention is applicable.

Standards for the WLAN technology have been developed as Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standards. IEEE802.11a and b use an unlicensed band at 2.4 GHz or 5 GHz. IEEE 802.11bprovides a transmission rate of 11 Mbps and IEEE 802.11a provides atransmission rate of 54 Mbps. IEEE 802.11g provides a transmission rateof 54 Mbps by applying Orthogonal Frequency Division Multiplexing (OFDM)at 2.4 GHz. IEEE 802.11n provides a transmission rate of 300 Mbps forfour spatial streams by applying Multiple Input Multiple Output(MIMO)-OFDM. IEEE 802.11n supports a channel bandwidth of up to 40 MHzand, in this case, provides a transmission rate of 600 Mbps.

Since the above-described standards for the WLAN technology maximallyuse bandwidth of 160 MHz and support eight spatial streams, IEEE802.11ax standardization is being discussed in addition to IEEE 802.11acstandard maximally supporting a rate of 1 Gbit/s.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method of, at astation, efficiently transmitting a signal in a wireless communicationsystem and an apparatus therefor.

More specifically, in IEEE 802.11ax which is a next-generation wirelesslocal area network (WLAN) among wireless communication systems, aresource allocation method using orthogonal frequency divisionalmultiple access (OFDMA) or multi-user multiple input multiple output(MIMO) is efficiently defined.

Another object of the present invention is to acquire various effectsunderstood from the detailed description of the present invention inaddition to the above-described object.

Technical Solution

The object of the present invention can be achieved by providing amethod for a first station (STA) to communicate signals in a wirelesslocal area network (WLAN), the method comprising preparing resourceallocation information for data to be transmitted to or received from aplurality of STAs and transmitting the resource allocation informationto the plurality of STAs, wherein the data is transmitted to or receivedfrom the plurality of STAs through a frequency band according to theresource allocation information, wherein the frequency band includes anull subband which is not used to transmit or receive the data, andwherein the resource allocation information includes a common resourceallocation bitmap for the plurality of STAs and indication informationindicating the null subband.

The resource allocation bitmap may indicate a subband configurationwhich is a resource allocation unit in the entire frequency band,depending on whether a subsequent bit is toggled from a preceding bit inthe resource allocation bitmap.

If a first subsequent bit is not toggled from a first preceding bit inthe resource allocation bitmap, a subband corresponding to the firstpreceding bit and a subband corresponding to the first subsequent bitmay be allocated to the same STA, and, if a second subsequent bit istoggled from a second preceding bit in the resource allocation bitmap, asubband corresponding to the second preceding bit and a subbandcorresponding to the second subsequent bit may be allocated to differentSTAs.

The indication information indicating the subband which is not used totransmit the data may include a null allocation field indicating that asubband preceding a subband allocated to a corresponding STA among theplurality of STAs indicates a null subband.

The resource allocation information may further include informationindicating order of allocating a plurality of subbands within thefrequency band to the plurality of STAs.

The resource allocation information may include ID fields, on eachsubband, for indicating identification information of an STA, to whicheach subband is allocated, among the plurality of STAs, and/orinformation on a size of a subband allocated to each STA. In this case,the indication information indicating the null subband can be indicatedbased on a specific value of the ID field. The specific value may be avalue other than values representing identifiers of the plurality ofSTAs. The specific value of the ID field on a specific subband, among aplurality of subbands within the frequency band, can indicate that thespecific subband is the null subband. On the other hand, theidentification field on other subband, other than the specific subband,having a value corresponding to an identifier of a specific STA amongthe plurality of STAs may indicate that the other subband is not thenull subband and the other subband is allocated to the specific STA.

The first station can be an AP (Access Point).

Here, the AP may transmit the resource allocation information to theplurality of STAs to solicit transmission of the data from the pluralityof STAs. Or, the AP may transmit the resource allocation information tothe plurality of STAs to transmit the data to the plurality of STAs.

The resource allocation information may further include an MU indicatorindicating whether a data transmission scheme indicates an OFDMA orMU-MIMO scheme.

In another aspect of the present invention, provided herein is a station(STA) for communicating signals in a wireless local area network (WLAN)including a processor configured to prepare resource allocationinformation for data to be transmitted to or received from a pluralityof STAs and a transceiver connected to the processor and configured totransmit the resource allocation information to the plurality of STAs,wherein the data is transmitted to or received from the plurality ofSTAs through a frequency band according to the resource allocationinformation, wherein the frequency band includes a null subband which isnot used to transmit or receive the data, and wherein the processorallows the resource allocation information to include a common resourceallocation bitmap for the plurality of STAs and indication informationindicating the null subband.

At this time, the resource allocation bitmap may indicate a subbandconfiguration which is a resource allocation unit in the entirefrequency band, depending on whether a subsequent bit is toggled from apreceding bit in the resource allocation bitmap.

More specifically, if a first subsequent bit is not toggled from a firstpreceding bit in the resource allocation bitmap, a subband correspondingto the first preceding bit and a subband corresponding to the firstsubsequent bit may be allocated to the same STA, and, if a secondsubsequent bit is toggled from a second preceding bit in the resourceallocation bitmap, a subband corresponding to the second preceding bitand a subband corresponding to the second subsequent bit may beallocated to different STAs.

The indication information indicating the subband which is not used totransmit the data may include a null allocation field indicating that asubband preceding a subband allocated to a corresponding STA among theplurality of STAs indicates a null subband.

The resource allocation information may further include informationindicating order of allocating a plurality of subbands to the pluralityof STAs.

The resource allocation information may include ID fields, one eachsubband, for indicating identification information of an STA, to whicheach subband is allocated, among the plurality of STAs, and/orinformation on a size of a subband allocated to each STA.

The indication information indicating the null subband may be indicatedbased on a specific value of the ID field.

The specific value of the ID field on a specific subband, among aplurality of subbands within the frequency band, may indicate that thespecific subband is the null subband.

Advantageous Effects

According to the present invention, a station can efficiently transmit asignal in a wireless communication system. More specifically, in IEEE802.11ax which is a next-generation wireless local area network (WLAN)among wireless communication systems, it is possible to efficientlyperform a resource allocation method using orthogonal frequencydivisional multiple access (OFDMA) or multi-user multiple input multipleoutput (MIMO).

The effects which can be obtained by the present invention are notlimited to the above-described effects and other effects which are notdescribed herein will become apparent to those skilled in the art fromthe following description.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of aWireless Local Area Network (WLAN) system.

FIG. 2 is a diagram illustrating another exemplary configuration of aWLAN system.

FIG. 3 is a diagram illustrating an exemplary structure of a WLANsystem.

FIGS. 4 to 8 are diagrams illustrating an example of a frame structureused in an IEEE 802.11 system.

FIG. 9 is a diagram showing an example of a PPDU format which may beused in the present invention.

FIG. 10 is a diagram illustrating an uplink among the concepts ofmulti-user transmission applicable to the present invention.

FIG. 11 is a diagram illustrating a station transmitting data using onlya partial bandwidth according to an embodiment of the present invention.

FIG. 12 is a diagram showing an example of defining a minimum resourceallocation unit regardless of bandwidth.

FIG. 13 is a diagram illustrating a method of configuring resourceallocation information according to a preferred embodiment of thepresent invention.

FIGS. 14 to 16 are diagrams showing additional examples for thoroughunderstanding of an embodiment of the present invention.

FIG. 17 is a diagram illustrating a method of configuring resourceallocation information when DL/UL OFDMA transmission and DL/UL MU-MIMOtransmission are used interchangeably in another embodiment of thepresent invention.

FIG. 18 is a block diagram showing an exemplary configuration of anaccess point (AP) apparatus (or a base station apparatus) and a stationapparatus (or UE apparatus) according to an embodiment of the presentinvention.

FIG. 19 is a diagram showing an exemplary structure of a processor of anAP apparatus or a station apparatus according to an embodiment of thepresent invention.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description set forth below in connection withthe appended drawings is intended as a description of exemplaryembodiments and is not intended to represent the only embodiments inwhich the concepts explained in these embodiments can be practiced. Thedetailed description includes details for the purpose of providing anunderstanding of the present invention. However, it will be apparent tothose skilled in the art that these teachings may be implemented andpracticed without these specific details.

The following embodiments are proposed by combining constituentcomponents and characteristics of the present invention according to apredetermined format. The individual constituent components orcharacteristics should be considered to be optional factors on thecondition that there is no additional remark. If required, theindividual constituent components or characteristics may not be combinedwith other components or characteristics. Also, some constituentcomponents and/or characteristics may be combined to implement theembodiments of the present invention. The order of operations to bedisclosed in the embodiments of the present invention may be changed toanother. Some components or characteristics of any embodiment may alsobe included in other embodiments, or may be replaced with those of theother embodiments as necessary.

It should be noted that specific terms disclosed in the presentinvention are proposed for convenience of description and betterunderstanding of the present invention, and the use of these specificterms may be changed to another format within the technical scope orspirit of the present invention.

In some instances, well-known structures and devices are omitted inorder to avoid obscuring the concepts of the present invention and theimportant functions of the structures and devices are shown in blockdiagram form. The same reference numbers will be used throughout thedrawings to refer to the same or like parts.

Exemplary embodiments of the present invention are supported by standarddocuments disclosed for at least one of radio access systems includingan Institute of Electrical and Electronics Engineers (IEEE) 802 system,a 3^(rd) Generation Project Partnership (3GPP) system, a 3GPP Long TermEvolution (LTE) system, and a 3GPP2 system. In particular, the steps orparts, which are not described to clearly reveal the technical idea ofthe present invention, in the embodiments of the present invention maybe supported by the above documents. All terminology used herein may besupported by at least one of the above-mentioned documents.

The following technologies can be applied to a variety of radio accesstechnologies, for example, CDMA (Code Division Multiple Access), FDMA(Frequency Division Multiple Access), TDMA (Time Division MultipleAccess), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA(Single Carrier Frequency Division Multiple Access), and the like. CDMAmay be embodied as wireless (or radio) technology such as UTRA(Universal Terrestrial Radio Access) or CDMA2000. TDMA may be embodiedas wireless (or radio) technology such as GSM (Global System for Mobilecommunications)/GPRS (General Packet Radio Service)/EDGE (Enhanced DataRates for GSM Evolution). OFDMA may be embodied as wireless (or radio)technology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA(Evolved UTRA).

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention.

In the entire specification, when a certain portion “includes” a certaincomponent, this indicates that the other components are not excluded,but may be further included unless specially described. The terms“unit”, “-or/er” and “module” described in the specification indicate aunit for processing at least one function or operation, which may beimplemented by hardware, software and a combination thereof.

FIG. 1 is a diagram illustrating an exemplary configuration of a WLANsystem.

As illustrated in FIG. 1, the WLAN system includes at least one BasicService Set (BSS). The BSS is a set of STAs that are able to communicatewith each other by successfully performing synchronization.

An STA is a logical entity including a physical layer interface betweena Media Access Control (MAC) layer and a wireless medium. The STA mayinclude an AP and a non-AP STA. Among STAs, a portable terminalmanipulated by a user is the non-AP STA. If a terminal is simply calledan STA, the STA refers to the non-AP STA. The non-AP STA may also bereferred to as a terminal, a Wireless Transmit/Receive Unit (WTRU), aUser Equipment (UE), a Mobile Station (MS), a mobile terminal, or amobile subscriber unit.

The AP is an entity that provides access to a Distribution System (DS)to an associated STA through a wireless medium. The AP may also bereferred to as a centralized controller, a Base Station (BS), a Node-B,a Base Transceiver System (BTS), or a site controller.

The BSS may be divided into an infrastructure BSS and an Independent BSS(IBS S).

The BSS illustrated in FIG. 1 is the IBSS. The IBSS refers to a BSS thatdoes not include an AP. Since the IBSS does not include the AP, the IBSSis not allowed to access to the DS and thus forms a self-containednetwork.

FIG. 2 is a diagram illustrating another exemplary configuration of aWLAN system.

BSSs illustrated in FIG. 2 are infrastructure BSSs. Each infrastructureBSS includes one or more STAs and one or more APs. In the infrastructureBSS, communication between non-AP STAs is basically conducted via an AP.However, if a direct link is established between the non-AP STAs, directcommunication between the non-AP STAs may be performed.

As illustrated in FIG. 2, the multiple infrastructure BSSs may beinterconnected via a DS. The BSSs interconnected via the DS are calledan Extended Service Set (ESS). STAs included in the ESS may communicatewith each other and a non-AP STA within the same ESS may move from oneBSS to another BSS while seamlessly performing communication.

The DS is a mechanism that connects a plurality of APs to one another.The DS is not necessarily a network. As long as it provides adistribution service, the DS is not limited to any specific form. Forexample, the DS may be a wireless network such as a mesh network or maybe a physical structure that connects APs to one another.

FIG. 3 is a diagram illustrating an exemplary structure of a WLANsystem. FIG. 3 shows an example of an infrastructure BSS including a DS.

In the example of FIG. 3, BSS1 and BSS2 configure an ESS. In the WLANsystem, a station operates according to MAC/PHY rules of IEEE 802.11.The station includes an AP station and a non-AP station. The non-APstation corresponds to an apparatus directly handled by a user, such asa laptop or a mobile telephone. In the example of FIG. 3, a station 1, astation 3 and a station 4 are non-AP stations and a station 2 and astation 5 are AP stations.

In the following description, the non-AP station may be referred to as aterminal, a wireless transmit/receive unit (WTRU), a user equipment(UE), a mobile station (MS), a mobile terminal, a mobile subscriberstation (MSS), etc. In addition, the AP corresponds to a base station(BS), a node-B, an evolved node-B (eNB), a base transceiver system(BTS), a femto BS, etc. in different wireless communication fields.

FIGS. 4 to 8 are diagrams illustrating an example of a frame structureused in an IEEE 802.11 system.

An STA may receive a physical layer packet data unit (PPDU). At thistime, the PPDU frame format may include a short training field (STF), along training field (LTF), a signal (SIG) field and a data field. Atthis time, for example, the PPDU frame format may be set based on thetype of the PPDU frame format.

For example, a non-high throughput (HT) PPDU frame format may include alegacy-STF (L-STF), a legacy-LTF (L-LTF), an SIG field and a data field.

In addition, any one of an HT-mixed format PPDU and an HT-Greenfieldformat PPDU may be set as the type of the PPDU frame format. At thistime, in the above-described PPDU format, additional (different typesof) STFs, LTFs and SIG fields may be included between the SIG field andthe data field.

In addition, referring to FIG. 5, a very high throughput (VHT) PPDUformat may be set. At this time, even in the VHT PPDU format, additional(different types of) STFs, LTFs and SIG fields may be included betweenthe SIG field and the data field. More specifically, in the VHT PPDUformat, at least one of a VHT-SIG-A field, a VHT-STF field, a VHT-LTFfield and a VHT SIG-B field may be included between the L-SIG field andthe data field.

At this time, the STF is a signal for signal detection, automatic gaincontrol (AGC), diversity selection, accurate time synchronization, etc.and the LTF is a signal for channel estimation, frequency errorestimation, etc. A combination of the STF and the LTF may be referred toas a PLCP preamble and the PLCP preamble may refer to a signal forsynchronization and channel estimation of an OFDM physical layer.

Referring to FIG. 6, the SIG field may include a RATE field and a LENGTHfield. The RATE field may include information about modulation andcoding rate of data. The LENGTH field may include information about thelength of data. Additionally, the SIG field may include a parity bit, anSIG TAIL bit, etc.

The data field may include a SERVICE field, a PLCP service data unit(PSDU) and a PPDU Tail bit and further may include a padding bit ifnecessary.

Referring to FIG. 7, some bits of the SERVICE field may be used forsynchronization of a descrambler in a receiver, and some bits may becomposed of reserved bits. The PSDU corresponds to a MAC protocol dataunit (PDU) defined at a MAC layer and may include data created/used at ahigher layer. The PPDU TAIL bit may be used to return an encoder to azero state. The padding bit may be used to adjust the length of the datafield to a predetermined length.

In addition, for example, as described above, the VHT PPDU format mayinclude the additional (different types of) STF, LTF and SIG fields. Atthis time, in the VHT PPDU, L-STF, L-LTF and L-SIG may be a part ofnon-VHT of the VHT PPDU. At this time, in the VHT PPDU, VHT-SIG-A,VHT-STF, VHT-LTF and VHT-SIG-B may be part of VHT. That is, in the VHTPPDU, regions for a Non-VHT field and a VHT field may be defined. Atthis time, for example, VHT-SIG-A may include information forinterpreting the VHT PPDU.

At this time, for example, referring to FIG. 8, VHT-SIG-A may becomposed of VHT SIG-A1 ((a) of FIG. 8) and VHT SIG-A2 ((b) of FIG. 8).At this time, each of VHT SIG-A1 and VHT SIG-A2 may include 24 data bitsand VHT SIG-A1 may be transmitted earlier than VHT SIG-A2. At this time,VHT SIG-A1 may include a BW field, an STBC field, a Group ID field, anNSTS/Partial AID field, a TXOP_PS_NOT_ALLOWED field and a Reservedfield. In addition, VHT SIG-A2 may include a Short GI field, a Short GINSYM Disambiguation field, an SU/MU[0] Coding field, an LDPC Extra OFDMSymbol field, an SU VHT-MCS/MU[1-3] Coding field, a Beamformed field, aCRC field, a Tail field and a Reserved field. Through this, informationon the VHT PPDU may be confirmed.

FIG. 9 is a diagram showing an example of a PPDU format which may beused in the present invention.

As described above, various types of PPDU formats may be set. At thistime, as an example, a new type of PPDU format may be proposed. The PPDUmay include an L-STF field, an L-STF field, an L-SIG field and a datafield. For example, a PPDU frame may further include a high efficiency(HE) SIG-A field, a HE-STF field, a HE-LTF field and a HE SIG-B field.For example, the HE SIG-A field may include common information. Forexample, the common information may include a bandwidth field, a guardinterval (GI) field, a length field and a BSS color field. For example,an L-part (L-STF, L-LTF and L-SIG) may be transmitted in the form of anSFN in units of 20 MHz in the frequency domain. In addition, forexample, the HE SIG-A field may be transmitted in the form of an SFN inunits of 20 MHz, similarly to the L part. For example, if a channel isgreater than 20 MHz, the L parts and the HE SIG-A field may beduplicated and transmitted in units of 20 MHz. In addition, the HE SIG-Bfield may be UE-specific information. For example, the user-specificinformation may include station AID, resource allocation information(e.g., allocation size), MCS, Nsts, coding, STBC, TXBF, etc. Forexample, the HE SIG-B field may be transmitted over the full bandwidth.

For example, referring to (b) of FIG. 9, the PPDU may be transmittedthrough a band of 80 MHz. At this time, the L part and the HE SIG-A partmay be duplicated and transmitted in units of 20 MHz and the HE SIG-Bfield may be transmitted over the full bandwidth of 80 MHz. However, theabove-described transmission method is exemplary and is not limited tothe above-described embodiments.

FIG. 10 is a diagram illustrating an uplink among the concepts ofmulti-user transmission applicable to the present invention.

As described above, the AP may acquire a TXOP for accessing a medium,occupy the medium through contention and transmit a signal. Referring toFIG. 10, an AP station may transmit a trigger frame to a plurality ofstations in order to perform UL MU transmission. At this time, forexample, the trigger frame may include information on resourceallocation location and size, station IDs, MCS, and MU type (=MIMO orOFDMA). That is, uplink multi-user (UL MU) transmission may mean that aplurality of stations as multiple users performs uplink transmission tothe AP station. At this time, the AP station may transmit the triggerframe to the plurality of stations such that the plurality of stationsperforms uplink data transmission.

The plurality of stations may transmit data to the AP after an SIFS haselapsed, based on a format indicated by the trigger frame. Thereafter,the AP may transmit ACK/NACK information to the station and perform ULMU transmission.

FIG. 11 is a diagram illustrating a station transmitting data using onlysome bandwidths according to an embodiment of the present invention.

As shown in FIG. 11, when the STA transmits a frame, the frame istransmitted using only a partial bandwidth, not a full bandwidth. Forexample, as shown in FIG. 11, the STA may transmit the frame with abandwidth (e.g., 5 MHz) less than 20 MHz. In this case, a good subbandof 5 MHz in 20 MHz may be selected and used to transmit the frame.

In FIG. 11, the STA transmits data through a second 5-MHz subband. Atthis time, the STA may transmit, in HE-SIGs, information on throughwhich subband data is transmitted. For example, in the bandwidthinformation included in HE-SIG, a reception side may be informed ofthrough which subband data is transmitted, through a bitmap of a minimumresource granularity unit.

In the above example, if a resource unit is 5 MHz (e.g., 56 subcarriertones), since a resource allocation bitmap having a size of 4 bits isconfigured and transmission is performed through a second resource unit(or subband), the bitmap is 0100 (that is, the frame is transmittedusing the second resource unit only). At this time, the bandwidth may beset to 20 MHz.

In association with the above description, hereinafter, examples of aminimum resource granularity unit will be described.

Basic Direction

(1) First resource unit? Regular resource unit (RRU) or basic tone unit(BTU); Hereinafter, RRU and BTU are used interchangeably and have thesame meaning.

The first resource unit is a large resource unit and, if possible, a BWsize of legacy Wi-Fi may be reused (e.g., 26 tones, 56 tones, 114 tones,242 tones, etc.). The size of the first resource unit may be fixedregardless of BW and increased according to BW.

(2) Second resource unit? Irregular resource unit (IRU) or small toneunit (STU); Hereinafter, IRU and STU are used interchangeably and havethe same meaning.

The second resource unit indicates a small resource unit and a method ofallocating left/right guard tones for interference mitigation to bothends of a BW and allocating an RRU and an IRU to the remaining regionexcept for central DC tones is defined. If possible, the number ofleft/right guard tones and DC tones may be maintained regardless of BW(e.g., left/right guard tone=6/5 or 7/6 tones, DC=5 or 3 tones, etc.).

An allocation method and the number of allocated tones may be set inconsideration of resource use efficiency, scalability according to BW,etc. In addition, the second resource unit may be predefined and may bedelivered through signaling (e.g., SIG) among various methods.

Method 1—BW Common Tone Unit (RRU/BTU Size=56 Subcarriers)

In this method, the size of the RRU/BTU is 56 subcarrier tones.

FIG. 12 is a diagram showing an example of defining a minimum resourceallocation unit regardless of bandwidth.

Since 56 subcarriers are equal to basic OFDM numerology of 20 MHz in alegacy Wi-Fi system, a conventional interleaver may be reused. At thistime, the size of the IRU/STU is 8 subcarrier tones. That is, assumethat RRU/BTU=56 and IRU/STU=8. However, assume that the minimumallocation unit of the IRU/STU is 2 IRUs/STUs (i.e., 16 tones).

Table 1 below shows the number of RUs, IRUs, and DCs and GIs per BW.

TABLE 1 BW # of RU # of IRU # of tones of DC + GS 20 MHz  4 (224 tones) 2 (16 tones) 16 (DC: 5, GS: 11 or DC: 3, GS: 13) 40 MHz  8 (448 tones) 6 (48 tones) 16 (DC: 5, GS:11 or DC: 3, GS: 13) 80 MHz 16 (896 tones)14 (112 tones) 16 (DC: 5, GS:11 or DC: 3, GS: 13)

As shown in Table 1 above, the number of remaining tones, that is, thenumber of DCs and GSs, is maintained as 16 (twice the number of IRUtones) regardless of BW.

-   -   (RU, IRU)=(56, 9)

If the IRU has a size of 9 subcarriers, per-BW numerology may be asshown in Table 2 below. A 160-MHz BW is obtained by repeatedly applying80 MHz twice.

TABLE 2 # of tones of BW # of RU # of MU DC + GS 20 MHz  4 (224 tones) 2(18 tones) 14 (DC: 3, GS:11) 40 MHz  8 (448 tones)  5 (45 tones) 19(DC: 8, GS: 11 or DC: 3, GS: 16) 80 MHz 16 (896 tones) 12 (108 tones) 20(DC: 3, GS: 17 or DC: 9, GS: 11)

In addition to the above-described examples, various combinations of(RU, IRU) are possible as follows. For example, (RU, IRU)=(26, 8), (RU,IRU)=(26, 6), (RU, IRU)=(114, 7), etc. may also be possible.

Method 2—Method of Changing RRU Size According to BW

-   -   (RRU=26/56/114 for 20/40/80 MHz, IRU=7)

In this method, the IRU is fixed to 14 regardless of BW. If two pilotsignals are used, 12 data tones are advantageous for various MCSdecoding methods. In particular, 80 MHz is advantageous for systematicdesign because RRU+IRU=114+14=128 is a divisor of 256.

The following tables show values which may be defined for eachbandwidth. More specifically, Table 3 shows 80 MHz, Table 4 shows 40 MHzand Table 5 shows 20 MHz.

TABLE 3 Number Number of Total number of tones allocation units of tonesRRU 114 8 912 IRU 7 14 98 left guard 6 right guard 5 DC 3

TABLE 4 Number Number of Total number of tones allocation units of tonesRRU 56 8 448 IRU 7 6 42 left guard 6 right guard 5 DC 11

TABLE 5 Number Number of Total number of tones allocation units of tonesRRU 26 8 208 IRU 7 4 28 left guard 6 right guard 5 DC 9

Hereinafter, a method of efficiently configuring resource allocationinformation based on the above description will be described.

As described above with respect to FIG. 11, in one embodiment of thepresent invention, when data is transmitted to a plurality of STAs forOFDMA/MU-MIMO transmission, assume that subbands which are not used fordata transmission are included in the full bandwidth. In this state, theresource allocation information may include a common resource allocationbitmap for the plurality of STAs and indication information indicatingsubbands which are not used for data transmission in the full frequencyband.

Hereinafter, examples of indicating the above-described resourceallocation information using the HE-SIG field will be described.

TABLE 6   Resource allocation information in HE-SIG field {  AID Resource Allocation Bitmap (e.g., 0100)  Per user parameter (e.g.,Nsts, STBC, MCS, TxBF, Coding) }

As shown in Table 6 above, the resource allocation information mayinclude a common resource allocation bitmap for a plurality of STAs. Theresource allocation bitmap may indicate a subband configuration, whichis a resource allocation unit of the entire frequency band, depending onwhether a subsequent bit is toggled from a preceding bit in the resourceallocation bitmap. More specifically, if a first subsequent bit is nottoggled from a first preceding bit in the resource allocation bitmap, asubband (e.g., SB 1) corresponding to the first preceding bit and asubband (e.g., SB 2) corresponding to the first subsequent bit may beallocated to the same STA. In contrast, if a second subsequent bit istoggled from a second preceding bit in the resource allocation bitmap, asubband (e.g., SB 2) corresponding to the second preceding bit and asubband (e.g., SB 3) corresponding to the second subsequent bit may beallocated to different STAs.

The resource allocation bitmap may start from 0 or 1 and Table 6 showsan example in which the resource allocation starts from 0. In theexample of Table 6, since a bit subsequent to 0 which is a first bit istoggled to 1, a first SB 1 and a second SB2 are allocated to differentSTA. In addition, since “0”, which is a third bit, is toggled from thepreceding bit, the SB 3 is allocated to an STA different from the STA,to which the SB 2 is allocated. In contrast, since “0”, which is afourth bit, is not togged from the preceding bit, an SB 4 correspondingthereto is allocated to the same STA as the SB 3 corresponding to thepreceding bit.

In summary, (1) SB 1 is allocated to STA 1, (2) SB 2 is allocated to STA2, and (3) SBs 3 and 4 are allocated to STA3. If a toggling based bitmapis used, it is possible to efficiently and flexibly allocate resourceswhile reducing signaling overhead of the plurality of STAs. In the abovedescription, it is assumed that the resource allocation order of theSTAs may be predetermined in order of STA 1, 2 and 3 or signaled inadvance.

The above-described resource allocation information may include thenumber of allocated streams (Nsts), space-time block coding (STBC),modulation and coding scheme (MCS) as per-user control information asshown in Table 6.

As a modification of Table 6, instead of the resource allocation bitmap,a start offset and an allocation size may be indicated as follows.

TABLE 7 Resource allocation information in HE-SIG field {  AID  Startoffset (e.g., resource unit (/sub-band) index or starting subcarrier) Allocation size (e.g., Total number of resource units/sub-bands orSpecific resource unit size)  Per user parameter (e.g., Nsts, STBC, MCS,TxBF, Coding) }

The signaling method shown in Table 6 above may cause a problem in thefollowing situations.

FIG. 13 is a diagram illustrating a method of configuring resourceallocation information according to a preferred embodiment of thepresent invention.

As shown in FIG. 13, when an AP transmits a trigger frame for UL MU(OFDMA), only a specific band may be used. Resource use information maybe included and transmitted in the trigger frame.

If it is assumed that SB 1 and SB 2 are allocated to STA 1 and SB 4 isallocated to STA 2 as shown in FIG. 13 and, for convenience, resourcesare allocated to the plurality of STAs by STA number, the toggling basedbitmap may be “1101”, because SBs 1 and 2 are allocated to the same STA,SB3 configures an allocation unit different from that of SBs 1 and 2 andSB4 configures an allocation unit different from that of SB3.

If presence of unused SBs in the entire band is not indicated as shownin FIG. 13, the bitmap may be erroneously interpreted as (1) allocationof SBs 1 and 2 to STA 1, (2) allocation of SB 3 to STA 2 and (3)allocation of SB 4 to STA 3.

Accordingly, in one preferred embodiment of the present invention,indication information, indicating subbands which are not used for datatransmission, may be further included and a null allocation fieldindicating whether a subband preceding a subband allocated to acorresponding STA of a plurality of STAs is a null subband may beincluded.

More specifically, upon UL MU transmission, when the AP transmits atrigger frame to allocate UL OFDMA resources (frame transmissionregion), a specific subband may be allocated to the STA through subbandoperation (the STA may perform transmission using a specific subband).At this time, which subband is used and which subband is not used (nullresource allocation) may be indicated in the trigger frame.

TABLE 8   Number of STA (N) For (1: N) {  Null allocation  AID  Per userparameter (e.g., Nsts, STBC, MCS, TxBF, Coding) } Resource AllocationBitmap

That is, FIG. 8 shows that resource allocation information may have auser-specific information field and a user common information field, theuser-specific information field may indicate presence/absence of “Nullallocation” in each of N STAs and AID and per-STA specific parameterinformation as an STA identifier, and the above-described resourceallocation bitmap information may be included as user commoninformation.

On such an assumption, the situation of FIG. 13 is applied. In theexample of FIG. 13, a third band is not used. Accordingly, if resourceallocation is indicated in the form of a bitmap, the followingconfiguration is possible. At this time, if the value of the nullallocation field is 1, it is assumed that null allocation is presentbefore allocation of the AID, but definition of the field value may bechanged.

TABLE 9 Null Resource Allocation Allocation AID Bitmap 1st 0 STA1's AID1101 2nd 1 STA2's AID

In Table 9, although the bitmap may be determined to be “1101” asdescribed above, presence of null allocation before allocation to STA 2may be indicated as null allocation information. Therefore, the bitmapmay not be erroneously interpreted as (1) allocation of SBs 1 and 2 toSTA 1, (2) allocation of SB 3 to STA 2 and (3) allocation of SB 4 to STA3, but may be accurately interpreted as (1) allocation of SBs 1 and 2 toSTA 1, (2) null allocation of SB 3 and (3) allocation of SB 4 to STA 2,as shown in FIG. 13.

FIGS. 14 to 16 are diagrams showing additional examples for thoroughunderstanding of an embodiment of the present invention.

As shown in FIG. 14, in the case of UL OFDMA allocation, in the triggerframe, the resource allocation bitmap is set to 1101 and the nullallocation fields are all set to 0 as shown in the following table.

TABLE 10 Null Resource Allocation Allocation AID Bitmap 1st 0 STA1's AID1101 2nd 0 STA2's AID

In FIG. 14, it can be implicitly seen from the information of Table 10that last allocation is null allocation. As shown in FIG. 15, if 20-MHzbands are all allocated to STAs 1, 2 and 3, resource allocationinformation shown in Table 11 below may be transmitted.

TABLE 11 Null Resource Allocation Allocation AID Bitmap 1st 0 STA1's AID1101 2nd 0 STA2's AID 3rd 0 STA3's AID

FIG. 16 shows an example of transmitting a frame using a bandwidth of 40MHz.

In FIG. 16, a frame is transmitted with a bandwidth of 40 MHz, the sizeof a resource unit (or subband) is 5 MHz (e.g., 56 tones), and a totalnumber of resource units is 8. At this time, OFDMA resources areallocated to three STAs and a seventh resource unit (subband) is a nullallocation unit.

In this example, the size of the resource allocation bitmap is 8 bitsand the values of the null allocation field and the resource allocationbitmap field may be set as follows.

TABLE 12 Null Resource Allocation Allocation AID Bitmap 1st 0 STA1's AID11110010 2nd 0 STA2's AID 3rd 1 STA3's AID

Hereinafter, various modifications of the above-described embodimentwill be described.

First, instead of inserting the null allocation field to every ID, anull allocation bitmap may be used as follows.

TABLE 13   Number of STA (N) For (1: N) { AID  Per user parameter (e.g.,Nsts, STBC, MCS, TxBF, Coding) } Resource Allocation Bitmap NullAllocation Bitmap

The size of the null allocation bitmap may be equal to the resourceallocation bitmap to indicate which subband (e.g., resource unit) is anull allocation unit. In FIGS. 13 to 15, the sizes of the resourceallocation bitmap and the null allocation bitmap may be 4 bits.

In FIG. 16, the sizes of the resource allocation bitmap and the nullallocation bitmap may be 8 bits. The following table shows the example(N=3) of FIG. 16.

TABLE 14 Resource Allocation NullAllocation AID Bitmap Bitmap 1st STA1'sAID 11110010 00000010 2nd STA2's AID 3rd STA3's AID

The size of the null allocation bitmap may be set to a total number ofallocations including null allocation. If the allocation bitmap isincluded, the size of the null allocation bitmap is determined based oninformation on the allocation bitmap (the number of toggles+1).

TABLE 15 Resource Allocation Bitmap Null Allocation Bitmap FIG. 131101   010 FIG. 14 001 FIG. 15 000 FIG. 16 11110010 0010 

If the number of allocations in the resource allocation bitmap and thenumber of AIDs are equal, the null allocation bitmap may not beincluded. In this case, this may be indicated through a 1-bit flag asfollows.

TABLE 16   Number of STA (N) For (1: N) {  AID  Per user parameter(e.g., Nsts, STBC, MCS, TxBF, Coding) } Resource Allocation Bitmap NAbitmap presences (1: Null allocation bitmap is included) If (NA bitmappresences==1) { Null Allocation Bitmap }

Alternatively, if the number of allocations and the number of AIDs arenot equal or the number of allocations is greater than the number ofAIDs, the null allocation bitmap may be included. If the number ofallocations in the resource allocation bitmap and the number of AIDs areequal, the null allocation bitmap may not be included.

TABLE 17   Number of STA (N) For (1: N) {  AID  Per user parameter(e.g., Nsts, STBC, MCS, TxBF, Coding) } Resource Allocation Bitmap If (N< Number of allocation (derived by allocation bitmap)) { Null AllocationBitmap }

If resource allocation is indicated in the form of an allocation size,not in the form of a bitmap, similar definition is possible.

TABLE 18   Number of allocation (M) For (1: M) {  Null allocation  If(Null allocation == 0) {   AID   Per user parameter (e.g., Nsts, STBC,MCS, TxBF, Coding)  }  Allocation size }

AID may be included only when null allocation is not performed (0).Allocation information is included by the total number of allocationsincluding null allocation.

The following table shows an example of applying FIG. 16.

TABLE 19 Null Allocation AID Allocation Size 1st 0 STA1's AID 4 2nd 0STA2's AID 2 3rd 1 Null Allocation 1 4th 0 STA3's AID 1

Instead of the null allocation field, a specific value which is not usedfor AID is used for indication. That is, an unallocated value may beused. For example, if all AID bits are set to 0 or 1, this indicates anull allocation value.

TABLE 20   Number of AID/allocation (M) For (1: M) {  AID  Allocationsize  Per user parameter (e.g., Nsts, STBC, MCS, TxBF, Coding) }

The following table shows an example of applying the above-describedmethod to FIG. 16.

TABLE 21 M AID Allocation Size 1st STA1's AID 4 2nd STA2's AID 2 3rdSpecific AID (e.g. all 0s or 1 all 1s), Null Allocation 4th STA3's AID 1

Meanwhile, instead of the null allocation field, the null allocationbitmap may be used.

TABLE 22   Number of STA (N) For (1: N) {  AID  Allocation size  Peruser parameter (e.g., Nsts, STBC, MCS, TxBF, Coding) } Null allocationbitmap

The size of the null allocation bitmap may be determined by a totalnumber of resource units.

The following table shows an example of FIG. 16 when the size of thenull allocation bitmap is determined by the total number of resourceunits.

TABLE 23 N AID Allocation Size Null allocation bitmap 1st STA1's AID 400000010 2nd STA2's AID 2 3rd STA3's AID 1

Which resource unit is a null allocation bitmap may be checked throughthe null allocation bitmap.

The null allocation bitmap may be configured by the total number ofallocations including null allocation, instead of the resource units andindicate how many allocations are present before null allocation. Forexample, when the total number of allocations including null allocationis 8, the null allocation bitmap has 8 bits, a bit corresponding to nullallocation is set to 1 and a bit which does not correspond to nullallocation is set to 0, and vice versa (that is, a bit corresponding tonull allocation is set to 0 and a bit which does not correspond to nullallocation is set to 1). A total number of allocations may be deliveredto the STA through HE-SIG.

The above-defined field information (e.g., number of STAs/allocation(N/M), AID, allocation bitmap, null allocation field, null allocationbitmap, NA bitmap presences, etc.) may be included and transmitted inthe trigger frame (CTX) carrying an SIG field or resource allocationinformation or may be transmitted through another frame.

As described above, the proposed methods may be used not only for ULframe transmission but also for DL frame transmission (DLOFDMA/MU(SU)-MIMO).

<Case where OFDMA Transmission and MU-MIMO Transmission are UsedInterchangeably>

FIG. 17 is a diagram illustrating a method of configuring resourceallocation information when DL/UL OFDMA transmission and DL/UL MU-MIMOtransmission are used interchangeably in another embodiment of thepresent invention.

In the example of FIG. 17, a frame corresponding to STA 1 is transmittedthrough resource units (RUs) 1, 2, 3 and 4 (20 MHz) and framescorresponding to STA 2, STA 3, STA4 and STA 5 are transmitted throughRUs 5 and 6 (10 MHz) using MU-MIMO and frames corresponding to STA 6 andSTA 7 are transmitted through RUs 7 and 8 (5 MHz). At this time,resources may be allocated using the following method.

Method 1: Resources are allocated to STAs through the AIDs of the STAs.An example thereof is as follows.

TABLE 24   Resource Allocation Bitmap Number of STA (N) For (1: N) {  MUindication  AID  Per user parameter (e.g., Nsts, STBC, MCS, TxBF,Coding) }

MU indication: This indicates whether allocation of an STA for AID istransmitted using MU-MIMO. A first STA having MU-MIMO indication of 1becomes a first STA of an MU-MIMO region. MU-MIMO indication of 0indicates SU transmission.

If MU indication for a preceding STA is set to 1, an STA having MUindication of 1 uses the same resources as the preceding STA. If MUindication for a preceding STA is set to 1, an STA having MU indicationof 0 uses a next resource region of a resource region of the precedingSTA. The STA may acquire a resource region used thereby through aresource allocation bitmap. The following table shows an example ofapplying such a method to FIG. 17.

TABLE 25 Resource Allocation N AID MU indication Bitmap 1^(st) STA1'sAID 0 11110010 2nd STA2's AID 1 3rd STA3's AID 1 4th STA4's AID 1 5thSTA5's AID 1 6th STA6's AID 0 7th STA7's AID 0

Through the resource allocation bitmap set to 11110010, it can be seenthat a total of four resources is allocated and STAs 1, 6 and 7 are setto MU indication of 0 such that SU transmission is performed and STAs 3,4 and 5 perform transmission using the same resources as STA 2 usingMU-MIMO.

Since the number of contiguous 1s of the MU indication is indicated asone MU-MIMO allocation unit and 0 indicates one SU-MIMO indication, STAsmay know a total number of allocations through MU indicationinformation. That is, the total number of allocations is (the totalnumber of MU indications (0)+the number of groups of contiguous MUindications (1)). In the above example, since the number of MUindications (0) is 3 and the number of groups of contiguous MUindications (1) is 1, the total number of allocations is 4.

Another example of using MU indication will now be described.

MU indication: This indicates whether allocation of an STA for AID istransmitted using MU-MIMO. MU-MIMO indication of 0 indicates SUtransmission. A first MU STA has MU indication of 0 and an STA having MUindication of 1 uses the same resources as the preceding STA. If MUindication for a preceding STA is set to 1, an STA having MU indicationof 0 uses a next resource region of a resource region used by thepreceding STA. The STA may acquire a resource region used therebythrough a resource allocation bitmap. The following table shows anexample of applying such a method to FIG. 17.

TABLE 26 Resource allocation N AID MU indication bitmap 1^(st) STA1'sAID 0 11110010 2nd STA2's AID 0 3rd STA3's AID 1 4th STA4's AID 1 5thSTA5's AID 1 6th STA6's AID 0 7th STA7's AID 0

Instead of the resource allocation bitmap, an allocation size may beused.

TABLE 27 Number of allocation (M) For (1: M) {   MU indication   If (MUindication ==0) {   AID    Per user parameter (e.g., Nsts, STBC, MCS,TxBF, Coding)   Allocation size  } else {    Number of STA (N)    For(1:N) {     AID     Per user parameter (e.g., Nsts, STBC, MCS, TxBF,Coding)    }    Allocation size  } }

With respect to MU-MIMO, a necessary number of pieces of STA information(e.g., AID, MIMO info (Nsts, STBC, etc.)) may be included.

Method 2: When resources are allocated to STAs, one resource isallocated to a single user (e.g., STAs 1, 6 and 7 of FIG. 17) throughthe AID of the single STA and allocation of MU-MIMO (STAs 2, 3, 4 and 5of FIG. 17) uses GID.

TABLE 28 Number of allocation (M) For (1: M) {  MU-MIMO indication  If(MU-MIMO indication ==0) {  AID   Per user parameter (e.g., Nsts, STBC,MCS, TxBF, Coding)  }  Else {   GID   For (Max number of STA in GID) {   Per user parameter (e.g., Nsts, STBC, MCS, TxBF, Coding)   }  } }Resource Allocation Bitmap

Instead of the resource allocation bitmap, an allocation size may beused.

TABLE 29 Number of allocation (M) For (1: M) {  MU-MIMO indication  If(MU-MIMO indication ==0) {  AID   Per user parameter (e.g., Nsts, STBC,MCS, TxBF, Coding)   Allocation size  }  Else {   GID   Allocation size  For (Max number of STA in GID) {    Per user parameter (e.g., Nsts,STBC, MCS, TxBF, Coding)   }  } }

Instead of including MU-MIMO indication in each STA, the number ofresource allocations may be indicated in the form of a bitmap. A totalnumber of resource allocations may be directly included in HE-SIG or maybe checked by the UE based on the resource allocation bitmap.

Each bit of the bitmap indicates whether the resource unit correspondingto the resource allocation corresponding to each bit is allocated usingMU-MIMO or SU. Accordingly, the size of the MU-MIMO indication bitmap isdetermined by the total number of allocations of the resource allocationbitmap. For example, if the total number of allocated OFDMA resources is8, the MU-MIMO indication bitmap has 8 bits and indicates which resourceallocation unit uses MU-MIMO.

In addition, null allocation indication and MU allocation may be usedtogether as follows.

TABLE 30 Number of STA and null allocation (N) For (1: N) {   If (N>1) {  Flag (00: SU, 01: MU-MIMO, 10: Null allocation, 11; reserved)   If(Flag==(00∥01)) {   AID   Per user parameter (e.g., Nsts, STBC, MCS,TxBF, Coding)    }  } else {    AID    Per user parameter (e.g., Nsts,STBC, MCS, TxBF, Coding)  } } Allocation bitmap

Another use example is as follows.

TABLE 31 Number of STA and null allocation (N) For (1: N) {   If (N>1) {  Flag (00: SU or 1st MU, 10: MU from 2nd MU, 10: Null allocation, 11;reserved)   If (Flag==(00∥01)) {   AID   Per user parameter (e.g., Nsts,STBC, MCS, TxBF, Coding)    }  } else {    AID    Per user parameter(e.g., Nsts, STBC, MCS, TxBF, Coding)  } } Resource Allocation bitmap

In MU-MIMO, if GID is used instead of AID and the allocation size isused instead of the allocation bitmap, the resource allocationinformation may be configured as follows.

TABLE 32 Number of allocation (M)    For (1: M) { Flag bit (00: SUallocation, 01: MU-MIMO, 10: Null allocation, 11; reserved) If (Flag ==00) {     AID  Allocation size  Per user parameter (e.g., Nsts, STBC,MCS, TxBF, Coding) } Else If (Flag==(01)) {    GID      Allocation size     For (Max number of STA in GID) {       Per user parameter (e.g.,Nsts, STBC, MCS, TxBF, Coding)      }    }   }   Number of allocation(M)    For (1: M) {    Flag (00: SU or 1st MU, 10: MU from 2nd MU, 10:Null allocation, 11; reserved) If (Flag ==00) {     AID  Allocation size Per user parameter (e.g., Nsts, STBC, MCS, TxBF, Coding) } Else If(Flag==(01)) {    GID      Allocation size      For (Max number of STAin GID) {       Per user parameter (e.g., Nsts, STBC, MCS, TxBF, Coding)     }    }   }

FIG. 18 is a block diagram showing an exemplary configuration of anaccess point (AP) apparatus (or a base station apparatus) and a stationapparatus (or UE apparatus) according to an embodiment of the presentinvention.

The AP 100 may include a processor 110, a memory 120 and a transceiver130. The STA 150 may include a processor 160, a memory 170 and atransceiver 180.

The transceivers 130 and 180 may transmit/receive a radio frequency (RF)signal and implement a physical layer according to an IEEE 802 system,for example. The processors 110 and 160 may be respectively connected tothe transceivers 130 and 180 to implement a physical layer and/or a MAClayer according to the IEEE 802 system. The processors 110 and 160 maybe configured to perform operations according to combinations of one ormore of the various embodiments of the present invention describedabove. In addition, modules for implementing operations of the AP andthe STA according to the above-described embodiments of the presentinvention may be stored in the memories 120 and 170 and may be executedby the processors 110 and 160, respectively. The memories 120 and 170may be mounted inside or outside the processors 110 and 160 to beconnected to the processors 110 and 160 by known means, respectively.

The description of the AP apparatus 100 and the STA apparatus 150 isapplicable to the base station apparatus and the UE apparatus in otherwireless communication systems (e.g., LTE/LTE-A systems).

The detailed configurations of the AP and the STA apparatuses may beimplemented such that details described in the above embodiments of thepresent invention are independently applied or two or more embodimentsare simultaneously applied. In this case, overlapping details have beenomitted from the description for clarity.

FIG. 19 is a diagram showing an exemplary structure of a processor of anAP apparatus or a station apparatus according to an embodiment of thepresent invention.

The processor of the AP or the STA may have a plurality of layers. FIG.19 shows a MAC sublayer 3810 of a data link layer (DLL) and a physical(PHY) layer 3820 among the plurality of layers. As shown in FIG. 19, thePHY 3820 may include a physical layer convergence procedure (PLCP)entity 3821 and a physical medium dependent (PMD) entity 3822. The MACsublayer 3810 and the PHY layer 3820 may respectively include managemententities, which are respectively referred to as MAC sublayer managemententities (MLME) 3811. These entities 3811 and 3821 provide a layermanagement service interface, for operation of a layer managementfunction.

To provide accurate MAC operation, a station management entity (SME)3830 may be included in each STA. The SME 3830 is a management entityindependent of each layer, which is present in or off to one side of aseparate management plane. Although the functions of the SME 3830 arenot accurately described in detail in this specification, such an entity3830 collects layer-dependent state information from several layermanagement entities (LMEs) and sets layer-specific parameter values. TheSME 3830 may perform such functions on behalf of general systemmanagement entities and implement standard management protocols.

The entities shown in FIG. 19 may interact using various methods. FIG.19 shows an example of exchanging GET/SET primitives. An XX-GET.requestprimitive is used to request a given management information base (MIB)attribute (management information based attribute information) value. AnXX-GET.confirm primitive is used to return an appropriate MIB attributeinformation value if a status is “SUCCESS” and to, otherwise, returnerror indication in a status field. An XX-SET.request primitive is usedto request setting of an indicated MIB attribute value to a given value.If the MIB attribute value indicates a specific operation, execution ofthe specific operation is requested. An XX-SET.confirm primitive is usedto confirm that the indicated MIB attribute is set to the requestedvalue if a status is “SUCCESS” and to, otherwise, return an errorcondition in a status field. If the MIB attribute value indicates aspecific operation, this may indicate that the specific operation hasbeen performed.

As shown in FIG. 19, various MLME GET/SET primitives may be exchangedbetween the MLME 3811 and the SME 3830 via an MLME Service access point(SAP) 3850. Alternatively, various PLCM GET/SET primitives may beexchanged between the PLME 3821 and the SME 3830 via a PLME SAP 3860 andmay be exchanged between the MLME 3811 and the PLME 3870 via anMLME-PLME SAP 3870.

The above-described embodiments of the present invention can beimplemented by a variety of means, for example, hardware, firmware,software, or a combination thereof.

In the case of implementing the present invention by hardware, thepresent invention can be implemented with application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), a processor, a controller, amicrocontroller, a microprocessor, etc.

If operations or functions of the present invention are implemented byfirmware or software, the present invention can be implemented in theform of a variety of formats, for example, modules, procedures,functions, etc. Software code may be stored in a memory unit so that itcan be driven by a processor. The memory unit is located inside oroutside of the processor, so that it can communicate with theaforementioned processor via a variety of well-known parts.

The detailed description of the exemplary embodiments of the presentinvention has been given to enable those skilled in the art to implementand practice the invention. Although the invention has been describedwith reference to the exemplary embodiments, those skilled in the artwill appreciate that various modifications and variations can be made inthe present invention without departing from the spirit or scope of theinvention described in the appended claims. For example, those skilledin the art may use each construction described in the above embodimentsin combination with each other. Accordingly, the invention should not belimited to the specific embodiments described herein, but should beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein. Although the preferred embodiments of thepresent invention have been disclosed for illustrative purposes, thoseskilled in the art will appreciate that various modifications, additionsand substitutions are possible, without departing from the scope andspirit of the invention as disclosed in the accompanying claims. Suchmodifications should not be individually understood from the technicalspirit or prospect of the present invention.

Both apparatus and method inventions are mentioned in this specificationand descriptions of both of the apparatus and method inventions may becomplementarily applicable to each other.

INDUSTRIAL APPLICABILITY

Although it is assumed that the present invention is applied to an IEEE802.11 based wireless local area network (WLAN) system, the presentinvention is not limited thereto. The present invention is applicable tovarious wireless systems.

What is claimed is:
 1. A method for a first station (STA) to communicatewith a second STA in a wireless local area network (WLAN), the methodcomprising: receiving, by the first STA from the second STA, resourceallocation information for a plurality of STAs, including the first STA,communicating with the second STA using orthogonal frequency divisionalmultiple access (OFDMA) or multi-user multiple input multiple output(MU-MIMO); and receiving, by the first STA from the second STA, datathrough a frequency band based on the resource allocation information,wherein the frequency band includes a plurality of resource units, theplurality of resource units including a normal resource unit allocatedto one STA, and a multi-user resource unit which is a single resourceunit allocated to more than one STA among the plurality of STAs, whereinthe resource allocation information includes: a common resourceallocation information having a same value for the plurality of STAs,and informing a number of the plurality of resource units and each sizeof the plurality of resource units, a multi-user indication for a numberof STAs, among the plurality of STAs, to which the multi-user resourceunit is allocated, and multiple ID fields for correspondingidentification information of STA to which the normal resource unit orthe multi-user resource unit is allocated.
 2. The method of claim 1,wherein the ID fields include: one or more first ID fields informingcorresponding identification information of one or more STAsrespectively allocated to the normal resource units, and one or moresecond ID fields informing corresponding identification information ofone or more STAs allocated to the multi-user resource unit.
 3. Themethod of claim 1, wherein the plurality of resource units furtherincludes a null subband which is not used to receive the data.
 4. Themethod of claim 3, wherein the ID fields further include one or morethird ID fields informing the null subband by using a specific value ofthe ID field.
 5. The method of claim 4, wherein the specific value is avalue other than values representing identifiers of the plurality ofSTAs.
 6. A first station (STA) for communicating with a second STA in awireless local area network (WLAN), the first STA comprising:transceiver configured to receive resource allocation information for aplurality of STAs, including the first STA, communicating with thesecond STA using orthogonal frequency divisional multiple access (OFDMA)or multi-user multiple input multiple output (MU-MIMO), and to receivedata through a frequency band based on the resource allocationinformation from the second STA; and a processor connected to thetransceiver and configured to process the resource allocationinformation and the data, wherein the frequency band includes aplurality of resource units, the plurality of resource units including anormal resource unit allocated to one STA, and a multi-user resourceunit which is a single resource unit allocated to more than one STAamong the plurality of STAs, wherein the resource allocation informationincludes: a common resource allocation information having a same valuefor the plurality of STAs, and informing a number of the plurality ofresource units and each size of the plurality of resource units basedon, a multi-user indication for a number of STAs, among the plurality ofSTAs, to which the multi-user resource unit is allocated, and multipleID fields for corresponding identification information of STA to whichthe normal resource unit or the multi-user resource unit is allocated.7. The first STA of claim 6, wherein the ID fields include: one or morefirst ID fields informing corresponding identification information ofone or more STAs respectively allocated to the normal resource units,and one or more second ID fields informing corresponding identificationinformation of one or more STAs allocated to the multi-user resourceunit.
 8. The first STA of claim 6, wherein the plurality of resourceunits further includes a null subband which is not used to receive thedata.
 9. The first STA of claim 8, wherein the ID fields further includeone or more third ID fields informing the null subband by using aspecific value of the ID field.
 10. The first STA of claim 9, whereinthe specific value is a value other than values representing identifiersof the plurality of STAs.